JP5281386B2 - Polymer thin film, patterned medium, and production method thereof - Google Patents

Abstract

The present invention provides a method of manufacturing a high-molecular thin film having a fine structure from a block-copolymer compound containing a block copolymer A as a main constituent composed of at least a block chain A1 and a block chain A2, and a block copolymer B as an accessory constituent composed of a block chain B1 miscible with a polymeric phase P1 mainly composed of the block chain A1 and a block chain B2 miscible with a polymeric phase P2 mainly composed of the block chain A2, and a substrate having a surface on which the block-copolymer compound is applied and on which a pattern member formed of a second material is discretely arranged to a surface part formed of a first material.

Description

  The present invention relates to a polymer thin film having a fine structure formed by microphase separation of a polymer block copolymer on a substrate surface, a pattern medium obtained using the polymer thin film, and a method for producing the same. .

In recent years, with the miniaturization and high performance of electronic devices, energy storage devices, sensors, and the like, there is an increasing need to form a fine regular array pattern having a size of several nanometers to several hundred nanometers on a substrate. Therefore, establishment of a process capable of manufacturing such a fine pattern structure with high accuracy and low cost is required.
As a processing method of such a fine pattern, a top-down method represented by lithography, that is, a method of imparting a shape by finely carving a bulk material is generally used. For example, photolithography used for semiconductor microfabrication such as LSI manufacturing is a typical example.

  However, as the fineness of the fine pattern increases, the application of such a top-down method increases the difficulty in both the apparatus and the process. In particular, when the processing dimension of a fine pattern becomes as fine as several tens of nanometers, it is necessary to use an electron beam or deep ultraviolet light for patterning, which requires enormous investment in the apparatus. Further, when it becomes difficult to form a fine pattern using a mask, the direct drawing method must be applied, and thus the problem that the processing throughput is significantly reduced cannot be avoided.

  Under such circumstances, a process that applies a phenomenon in which a substance naturally forms a structure, that is, a so-called self-organization phenomenon, has attracted attention. In particular, the process applying the self-organization phenomenon of the polymer block copolymer, so-called microphase separation, can form a fine regular structure having various shapes of several tens to several hundreds of nanometers by a simple coating process. Is an excellent process. For example, when different types of polymer segments that make up the polymer block copolymer do not mix with each other (incompatible), these polymer segments have specific regularity due to phase separation (microphase separation). The microstructure is self-organized.

As an example of forming a fine ordered structure using such a self-organization phenomenon, a polymer block copolymer thin film comprising a combination of polystyrene and polybutadiene, polystyrene and polyisoprene, polystyrene and polymethyl methacrylate, etc. Is known as a technique for forming a structure such as a hole and a line-and-space on a substrate by using as an etching mask.
According to the microphase separation phenomenon of such a polymer block copolymer, a polymer having a structure in which microdomains of fine spherical, columnar and plate-like bodies are regularly arranged, which is difficult to achieve by a top-down method. A thin film can be obtained.
However, in general, the self-organization phenomenon including the microphase separation phenomenon has the following problems in applying to patterning.

  Patterning using the self-organization phenomenon is superior in short-range regularity but inferior in long-range order, has the problem that defects and grain boundaries exist, and that it is difficult to form an arbitrary pattern. is there. In particular, since self-organization uses a structure formed by nature, that is, a structure that is the smallest in terms of energy, it is generally difficult to obtain a structure other than a regular structure having a period specific to the material. Therefore, there is a drawback that the application range of this patterning is limited. Conventionally, the following two methods are known as methods for overcoming these drawbacks.

  The first method is a method of developing microphase separation by processing a groove on the surface of a substrate and forming a polymer block copolymer therein. According to this method, the microstructures developed by the microphase separation are arranged along the wall surface of the groove, so that the directionality of the regular structure can be controlled in one direction, and the long-range order is improved. Moreover, since the regular structure is filled along the wall surface, the occurrence of defects is also suppressed. Such an effect is known as a graphoepitaxy effect, but decreases as the groove width increases. When the groove width is approximately 10 times the period of the regular structure, the regular structure is formed at the center of the groove. Disturbance occurs. Moreover, since it is necessary to process a groove on the substrate surface, it cannot be used for applications that require a flat surface. Further, in this method, the regular structure can be oriented in the direction along the groove, but the pattern cannot be arbitrarily controlled any more.

  The second method is a method of chemically patterning the substrate surface and controlling the structure developed by microphase separation by chemical interaction between the substrate surface and the polymer block copolymer (for example, Patent Documents). 1 and Patent Document 2). FIG. 14 referred to here is a conceptual perspective view for explaining a conventional method of chemically patterning the surface of the substrate.

  As shown in FIG. 14, in this method, a top-down approach is performed so that the affinity for each block chain (the first segment 301 and the second segment 302) constituting the polymer block copolymer 303 is different. A chemically patterned substrate 305 having a surface patterned by a technique is used. In this method, a polymer block copolymer 303 is formed on the surface of the chemically patterned substrate 305 to develop microphase separation. For example, when a polymer diblock copolymer made of polystyrene and polymethyl methacrylate is used as the polymer block copolymer 303, the surface of the chemically patterned substrate 305 is made of a region 307 having good affinity with polystyrene and polymethyl methacrylate. A chemical pattern is formed by dividing into a region 308 having excellent affinity with methacrylate. If the chemical pattern shape is equivalent to the microphase separation structure of the polystyrene-polymethylmethacrylate diblock copolymer, it is made of polystyrene on the region 307 having good affinity for polystyrene during the microphase separation. A continuous phase 306 is arranged, and a columnar microdomain 304 made of polymethyl methacrylate is arranged on a region 308 having good affinity with polymethyl methacrylate.

That is, according to this method, it is possible to arrange the microphase separation structure along the mark chemically placed on the substrate surface. In addition, according to this method, since a chemical pattern is formed by a top-down method, the long-range order of the obtained pattern is ensured by a top-down method, and is excellent in regularity over a wide range and has few defects. A pattern can be obtained. In the following description, this method may be referred to as a micro-domain chemical registration method.
US Pat. No. 6,746,852 US Pat. No. 6,926,953

  However, in the conventional chemical registration method, when the processing size becomes as fine and high as several tens of nanometers, defects and pattern shapes are likely to be disturbed, and the resulting microphase separation structure may be adversely affected. Become. For this reason, chemical patterns are discretely arranged at positions where microdomains are formed. In other words, microdomains are also formed between chemically placed marks by interpolation of self-organization. Thus, it is conceivable to form a microphase separation structure.

However, when the ratio between the density of microdomains and the density of patterns has a relationship of n: 1 (where n represents a number exceeding 1), there are the following problems.
In other words, when the micro block separation of the polymer block copolymer formed on the substrate surface is expressed, the part where the chemical pattern is formed has a structure in which the micro domain is upright with respect to the substrate. In a portion where no pattern is formed, the microdomains are not oriented perpendicularly to the substrate, and a high-density pattern in which a chemical pattern is interpolated may not be obtained. For this reason, it has been difficult to obtain a pattern with few defects without losing the long-range order uniformly in the entire region of the chemical pattern. Incidentally, this problem becomes more prominent as the value of n increases.

  Accordingly, an object of the present invention is to provide a polymer thin film having a fine structure composed of a microphase-separated structure having excellent long-range order and few defects, a patterned medium obtained using this polymer thin film, and these It is to provide a manufacturing method.

The present invention that solves the above-described problems includes a first step of disposing a polymer layer containing a polymer block copolymer composition on a substrate surface, micro-phase separation of the polymer layer, and regularly in a continuous phase. In the method for producing a polymer thin film having a microstructure including a second step of forming an arrayed microdomain, the polymer block copolymer composition includes at least a polymer block chain A1 and a polymer block chain A2. A polymer block chain B1 compatible with a polymer phase P1 having the polymer block chain A1 as a main component, and the polymer block chain A2 as a main component. A polymer block copolymer B having a polymer block chain B2 compatible with the polymer phase P2 to be blended as a subcomponent, and the molecular weight Mn (A1) of the polymer block chain A1 The molecular weight of the block chain A2 Mn (A2), and the molecular weight of the polymer block chain Mn (B2) satisfy the following relation (1):
Relational expression (1): Mn (A2)> Mn (A1) and Mn (B2)> Mn (A2)
And the substrate surface is formed by discretely arranging pattern members made of the second material on the surface made of the first material. In the second step, the substrate surface has a height higher than that of the surface made of the first material. The interfacial tension of the molecular phase P1 is smaller than the interfacial tension with the surface made of the second material, and the interfacial tension of the polymer phase P2 with respect to the surface made of the first material is the surface made of the second material. much larger than the interfacial tension, the natural period do the following relationships with a dry film thickness t and the microdomains of the coating film of the block copolymer composition of the substrate surface (2) between:
Relational expression (2) (m + 0.3) × do <t <(m + 0.7) × do
(In the relational expression (2), m represents an integer of 3 to 5)
It is characterized by satisfying .

  Moreover, the manufacturing method of the patterned medium of the present invention that solves the above-described problem is any of the continuous phase and the microdomain of the polymer thin film obtained on the substrate by the method of manufacturing the polymer thin film having the fine structure described above. It includes a step of removing one of them.

  Moreover, the microstructure of the present invention that solves the above-described problems is characterized by comprising a polymer thin film obtained by the method for producing a polymer thin film having the microstructure described above.

  Moreover, the patterned medium of the present invention that solves the above problems is obtained by the above-described method for manufacturing a patterned medium.

  In addition, the pattern medium of the present invention that solves the above-described problems may be a pattern medium that is copied by transferring the pattern arrangement by the imprint method using the above-described pattern medium as an original plate.

  According to the present invention, a polymer thin film having a fine structure composed of a microphase-separated structure having excellent long-range order and few defects, a pattern medium obtained using the polymer thin film, and a method for producing the same Can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
First, a method for producing a polymer thin film having a fine structure will be described. Here, a manufacturing method (manufacturing method by a chemical registration method) of a polymer thin film having a structure in which microdomains formed by columnar bodies (cylinders) are upright on a substrate is shown. FIGS. 1A to 1D referred to here are process explanatory views of a method for producing a polymer thin film having a fine structure.

  FIG. 1A shows a substrate 201 for forming a polymer thin film M (see FIG. 1D) having a structure to be described later. The substrate 201 is patterned as follows.

As shown in FIG. 1B, the surface of the substrate 201 is patterned into a surface made of the first material 106 and a surface made of the second material 107 having different chemical properties.
Next, as shown in FIG. 1C, a coating film 202 of a polymer block copolymer composition described later is formed on the surface of the substrate 201. This step corresponds to the “first step” in the claims.

  In this production method, as shown in FIG. 1 (d), the polymer block copolymer composition of the coating film 202 is microphase-separated on the substrate 201, whereby a polymer block chain A2 (see FIG. 2) in the continuous phase 204 composed of the polymer phase P2 mainly composed of the polymer phase P1 and the micro domain 203 composed of the polymer phase P1 composed mainly of the polymer block chain A1 (see FIG. 2) described later (columnar body). Forms a phase-separated microstructure. This step corresponds to the “second step” in the claims.

  At this time, the polymer phase P1 (see FIG. 1 (d)) mainly composed of the polymer block chain A1 (see FIG. 2) is formed on the surface made of the first material 106 shown in FIG. 1 (b). The wettability is better than that of the polymer phase P2 (see FIG. 1 (d)) whose main component is the polymer block chain A2 (see FIG. 2). The polymer phase P2 mainly composed of the polymer block chain A2 (see FIG. 2) is more than the polymer phase P1 mainly composed of the polymer block chain A1 with respect to the surface made of the second material 107. Good wettability. In other words, the interfacial tension of the polymer phase P1 with respect to the surface made of the first material 106 is smaller than the interfacial tension with the surface made of the second material 107, and the polymer phase P2 with respect to the surface made of the first material 106 Is greater than the interfacial tension with the surface made of the second material 107.

  And the chemical state of the surface of the substrate 201 is designed in this way, and preferably the film thickness t of the coating film 202 of the polymer block copolymer composition satisfies a predetermined range satisfying the relational expression (2) described later. By controlling so that, as shown in FIG. 1D, the microdomain 203 (columnar body) composed of the polymer phase P1 mainly composed of the polymer block chain A1 (see FIG. 2) is the first. A continuous phase 204 composed of the polymer phase P2 mainly composed of the polymer block chain A2 (see FIG. 2) is disposed on the surface composed of the second material 107. That is, the polymer thin film M having a fine structure composed of the microdomain 203 and the continuous phase 204 can be formed on the substrate 201. Note that the micro domain 203 formed in the second material 107 is interpolated as described later.

Next, materials and the like used for the manufacturing method of the polymer thin film M having the microstructure of the present invention will be described.
(Polymer block copolymer composition)
The polymer block copolymer composition comprises at least a polymer block copolymer A composed of at least a polymer block chain A1 and a polymer block chain A2, and a polymer comprising the polymer block chain A1 as a main component. A polymer block copolymer B having a polymer block chain B1 compatible with the phase P1 and a polymer block chain B2 compatible with the polymer phase P2 mainly composed of the polymer block chain A2 is used as a subcomponent. It is blended as

  By such a combination, for example, the polymer block copolymer composition is phase-separated and the microdomain 203 (see FIG. 1 (d)) containing the polymer block chain A1 as a main component, and the polymer block When the continuous phase 204 mainly composed of the chain A2 (see FIG. 1D) is developed, the polymer block chain B1 is selectively compatible with the microdomain 203, and the polymer block chain B2 is the continuous phase. A state of being selectively compatible with 204 is realized.

Examples of the polymer block copolymer A include a polystyrene-block-polymethyl methacrylate copolymer (hereinafter referred to as “PS-b”) in which polymethyl methacrylate is used as the polymer block chain A1 and polystyrene is used as the polymer block chain A2. -PMMA ") and polystyrene-block-polydimethylsiloxane having polydimethylsiloxane as the polymer block chain A1 and polystyrene as the polymer block chain A2, and the like. The combination is not limited to a molecular block copolymer, and can be widely used as long as it is a combination that exhibits microphase separation.
The polymer block copolymer A may be synthesized by an appropriate method. However, in order to improve the regularity of the microphase separation structure, a synthesis method having a molecular weight distribution as narrow as possible is preferable. Examples of applicable synthesis methods include living polymerization methods.

  As the polymer block copolymer B, for example, when PS-b-PMMA is used as the polymer block copolymer A, the polymer block copolymer B has the following polymer block chain B1 and polymer block chain B2. Is mentioned.

  As the above-described polymer block chain B1, the same polymethyl methacrylate and polydimethylsiloxane as the polymer block chain A1 can be applied, and other polymers such as styrene-acrylonitrile are compatible with these polymethyl methacrylates. Copolymer, acrylonitrile-butadiene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylphenol-styrene copolymer Examples thereof include vinylidene chloride-acrylonitrile copolymer, vinylidene fluoride homopolymer, and the like.

As the above-described polymer block chain B2, the same polystyrene as the polymer block chain A2 can be applied, and polymers compatible with polystyrene such as polyphenylene ether, polymethyl vinyl ether, poly α-methyl styrene, nitro Cellulose or the like can be applied.
Even in such a polymer, since the degree of compatibility may vary depending on the molecular weight, concentration, temperature, and composition, it is desirable to appropriately set these conditions for good compatibility. .

Next, the relationship between the molecular weights of the polymer block copolymer A and the polymer block copolymer B will be described. When the molecular weight of the polymer block chain A1 is Mn (A1), the molecular weight of the polymer block chain A2 is Mn (A2), and the molecular weight of the polymer block chain B2 is Mn (B2), these are the following relationships: It is necessary to satisfy Formula (1).
Relational expression (1): Mn (A2)> Mn (A1) and Mn (B2)> Mn (A2)

  By combining the polymer block copolymer A and the polymer block copolymer B having a molecular weight satisfying the relational expression (1), Macross, which is a problem in pattern formation by a chemical registration method, It is possible to manufacture a polymer thin film having a fine structure in which copic phase separation is suppressed and variation in pattern size and defects are reduced.

  The state of the polymer block copolymer composition satisfying the relational expression (1) can be expressed as follows by taking the length of the polymer block chain as an example. FIG. 2 referred to here is a conceptual diagram showing a state of polymer block chains in the polymer block copolymer composition.

As shown in FIG. 2, as the polymer block copolymer composition C, for example, the polymer block chain A2 of the polymer block copolymer A is more than the polymer block chain A1 of the polymer block copolymer A. A polymer having a large molecular weight Mn and a polymer block chain B2 of the polymer block copolymer B having a molecular weight Mn larger than the polymer block chain A2 of the polymer block copolymer A can be used.
In the polymer block copolymer composition C shown in FIG. 2, the length of the polymer block chain A1 of the polymer block copolymer A and the molecular weight of the polymer block chain B1 of the polymer block copolymer B are as follows. The same Mn is used.

In the polymer block copolymer composition as described above, it is desirable that the mass fraction of the polymer block copolymer A as the main component occupies the whole is 75% or more and 95% or less.
By setting the mass fraction to be within this range, the macromolecular block copolymer A and the macromolecular block copolymer B, which is a secondary component, are macroscopically phase separated during microphase separation. , Can be more reliably prevented.

The molecular weight and composition ratio of the polymer block chain constituting the polymer block copolymer composition may be set according to the shape and size of the target pattern while satisfying the above conditions.
Incidentally, the polymer block copolymer composition includes a polymer phase P1 (see FIG. 1 (d)) whose main component is the polymer block chain A1 and a polymer phase P2 whose main component is the polymer block chain A2 (see FIG. 1). 1 (d)), the structure of the polymer phase P1 is more than that of the polymer phase P2 as the proportion of the polymer phase P1 in the total volume increases from 0% to 50%. From the microdomain of the spherical body regularly arranged in the matrix, the microdomain of the plate-like body (lamella-like body) composed of the polymer phase P1 and the plate-shape composed of the polymer phase P2 through the microdomain of the columnar body. It changes into a structure in which the microdomains of the body are arranged alternately.

  When the ratio of the polymer phase P1 to the total volume further increases, the structure of the polymer phase P1 regularly arranges the microdomains of the columnar body made of the polymer phase P2 from the microdomains of the plate-like body. Through the structure that has become a matrix, the structure changes to a structure that has a matrix in which spherical microdomains composed of the polymer phase P2 are regularly arranged.

The size of the pattern is mainly defined by the total molecular weight of the polymer block copolymer A, and the pattern size increases as the total molecular weight increases.
The above-described polymer block copolymer A has been described as an example of a polymer diblock copolymer formed by bonding two kinds of polymer block chains A1 and A2, but the present invention is limited to this. Other than that, other ABA type polymer triblock copolymers, linear polymer block copolymers such as ABC type polymer block copolymers composed of three or more kinds of polymer block chains, or star type high polymers It may be a molecular block copolymer.

  As described above, the polymer block copolymer composition in the present embodiment expresses the structures of columnar bodies and plate-like bodies by microphase separation. And as above-mentioned, the structure and size of the pattern which a polymer block copolymer composition expresses become intrinsic | native according to the molecular weight and composition of a polymer block copolymer. Here, the period of the regular structure that appears by microphase separation is defined as the natural period do.

  FIG. 3A referred to here is a perspective view schematically showing a state in which the polymer block copolymer composition is microphase-separated to form a columnar pattern structure, and FIG. It is a perspective view which shows typically a mode that the polymer block copolymer composition formed the structure of the pattern of a plate-shaped body by carrying out micro phase separation.

  As shown in FIG. 3 (a), the structure in which the polymer block copolymer composition C forms a columnar pattern by microphase separation on the substrate 201 is packed with hexagonal microdomains 203 of each columnar body. Are arranged regularly. In this case, the natural period do is defined by the lattice spacing of the hexagonal array. As shown in FIG. 3B, the natural period do in a structure in which the microdomain 203 of the plate-like body and the continuous phase 204 of the plate-like body are alternately continued is defined by the interval between the plate-like bodies. The

(substrate)
In the chemical registration method, as described above, the surface of the substrate 201 shown in FIG. 1B is divided into a surface made of the first material 106 and a surface made of the second material 107 having different chemical properties. Patterned. Here, a method for patterning the surface of the substrate 201 will be mainly described.

  The material of the substrate 201 shown in FIG. 1A is not particularly limited, and for example, inorganic materials such as glass and titania, semiconductors such as silicon and GaAs, metals such as copper, tantalum, and titanium, The thing which consists of organic substances like an epoxy resin and a polyimide is mentioned. The material of the substrate 201 may be appropriately selected according to the purpose.

  A method for patterning the surface of the substrate 201 will be described. 4A to 4G to be referred to are process explanatory views of a method for patterning the surface of the substrate. Here, the case where the polymer block copolymer composition whose main component polymer block copolymer A is PS-b-PMMA is used will be described. That is, as shown in FIG. 1 (d), by microphase separation, a continuous phase 204 mainly composed of a polymer block chain A2 (polymer phase P2) made of polystyrene and a polymer block chain made of polymethyl methacrylate. This is based on the premise that the microdomain 203 of the columnar body mainly composed of A1 (polymer phase P1) is developed.

First, as shown in FIG. 4A, in this method, first, a substrate 201 is prepared. Here, a substrate 201 made of silicon was prepared.
Next, as shown in FIG. 4B, a chemical modification layer 401 is formed on the surface of the substrate 201 in order to make the entire surface of the substrate 201 more easily wetted with polystyrene than with polymethylmethacrylate.

  Examples of the method for forming the chemically modified layer 401 include a method of forming a monomolecular film by applying a silane coupling agent or the like to the surface of the substrate 201 and a method of introducing a polymer compound to the surface of the substrate 201. Can be mentioned. A specific example of the method for forming the monomolecular film includes a method of forming a monomolecular film of a silane compound having a phenethyl group on the surface of the substrate 201 using, for example, phenethyltrimethoxysilane.

  Examples of the method for introducing the polymer compound include a method of grafting a polymer compound compatible with polystyrene onto the surface of the substrate 201. The grafting of the polymer compound is performed by first introducing a functional group serving as a polymerization initiation base point onto the surface of the substrate 201 by a coupling method or the like, and polymerizing the polymer compound from the polymerization initiation point. There is a method of synthesizing a polymer compound having a functional group to be coupled in the terminal or main chain, and then coupling to the surface of the substrate 201. In particular, the latter method is simple and recommended.

  Here, a method of grafting polystyrene on the surface of the substrate 201 made of silicon in order to make the surface of the substrate 201 made of silicon preferred (wettability) of polystyrene will be described more specifically.

  In this method, polystyrene having a hydroxyl group at the terminal is synthesized by a predetermined living polymerization. Next, the density of the hydroxyl groups of the natural oxide film formed on the surface of the substrate 201 is increased by exposing the substrate 201 to oxygen plasma or immersing the substrate 201 in a piranha solution. Then, polystyrene having a hydroxyl group at the terminal is dissolved in a solvent such as toluene, and a film is formed on the substrate 201 by using a spin coat method or the like. Thereafter, the obtained substrate 201 is heated at a temperature of about 170 ° C. for about 72 hours in a vacuum atmosphere using a vacuum oven or the like. By this treatment, the hydroxyl group on the surface of the substrate 201 and the hydroxyl group at the end of polystyrene are dehydrated and condensed, and the surface of the substrate 201 and polystyrene are bonded. Finally, the substrate 201 is washed with a solvent such as toluene, and the unbonded polystyrene is removed from the substrate 201, whereby the substrate 201 on which polystyrene is grafted is obtained.

  The molecular weight of the polymer compound grafted onto the surface of the substrate 201 is not particularly limited, but if a polymer compound having a molecular weight of about 1000 to 10,000 is used, an ultrathin film of a polymer compound with a thickness of several nm is formed on the surface of the substrate 201. This is desirable.

  Next, the chemically modified layer 401 provided on the surface of the substrate 201 is patterned. As a patterning method, a known patterning technique such as photolithography or an electron beam (EB) drawing method may be applied according to a desired pattern size.

  Specifically, as shown in FIG. 4C, a resist film 402 is formed on the surface of the chemically modified layer 401, and as shown in FIG. 4D, the resist film 402 is patterned by exposure, By performing the development process shown in FIG. 4E, the resist film 402 is formed into a pattern mask. Then, as shown in FIG. 4F, an etching process such as an oxygen plasma process is performed through the resist film 402 that has been subjected to pattern masking so as to correspond to the resist film 402 that has been subjected to pattern masking. The chemically modified layer 401 is partially removed. Next, as shown in FIG. 4G, the remaining resist film 402 is removed, whereby a patterned chemically modified layer 401 is obtained on the substrate 201.

  According to such a method, a substrate having a chemically modified layer 401 made of patterned polystyrene on the surface of a substrate 201 made of silicon can be obtained. More specifically, the surface of the chemically modified substrate 201 is divided and patterned into a surface where silicon is exposed and a surface made of a chemically modified layer 401 made of polystyrene. Incidentally, the surface made of the chemical modification layer 401 here corresponds to the “surface made of the first material” in the claims, and the portion where the silicon is exposed is the “second surface” in the claims. It corresponds to the “surface made of material”.

  In this chemically modified substrate 201, since the silicon surface has a property of favoring polymethyl methacrylate over polystyrene, as a result, the polymer phase P1 made of polymethyl methacrylate is formed on the silicon surface. To separate. In addition, since the surface made of the chemically modified layer 401 has a property of favoring polystyrene over polymethyl methacrylate, the polymer phase P2 made of polystyrene is microphase-separated on the surface of the chemically modified layer 401 as a result.

As described above, the method for patterning the surface of the substrate 201 has been described for the polymer block copolymer composition mainly composed of PS-b-PMMA. However, in the other polymer block copolymer compositions, Even if it exists, what is necessary is just to pattern the substrate surface chemically by the same method.
Note that the steps shown in FIGS. 4C to 4G are examples, and other methods can be used as long as the chemical modification layer 401 (see FIG. 4B) provided on the surface of the substrate 201 can be patterned. May be used.

  And although the chemical modification layer 401 obtained by such a process is formed as a thin film on the board | substrate 201 as shown in FIG.4 (g), this invention is not limited to this.

FIGS. 5A and 5B referred to here are schematic views showing another embodiment in which a chemically modified layer is arranged on a substrate.
As shown in FIG. 5A, the chemically modified layer 401 may be discretely embedded in the substrate 201. As shown in FIG. It may be discretely embedded in a thin film 401 ′ formed on the surface of the substrate 201 and having a chemical property different from that of the chemically modified layer 401. As a method of forming the substrate shown in FIG. 5B, for example, after the chemical modification layer 401 is formed on the substrate 201 as shown in FIG. A method of forming a thin film 401 ′ different from the chemically modified layer 401 on the exposed surface portion of the substrate 201 by applying the above is exemplified.

Next, the chemical registration method used in this embodiment will be described.
The chemical registration method improves the long-range order of the microphase separation structure formed by self-organization of the polymer block copolymer by a chemical mark provided on the surface of the substrate 201 (see FIG. 4 and the like). It is a technique. According to this chemical registration method, chemical mark defects are interpolated by self-organization of the polymer block copolymer.

  FIG. 6 (a-1) referred to here is a conceptual diagram showing how a defect of a chemical mark is interpolated using the polymer block copolymer composition in the present embodiment, and FIG. 6 (a-). 2) is a cross-sectional view taken along line XX in FIG. FIG. 6B-1 is a conceptual diagram showing a state in which the defect of the chemical mark is not interpolated using the polymer block copolymer in the comparative example, and FIG. It is a YY sectional view of -1).

  When the above-described polymer block copolymer composition is used in this embodiment, as shown in FIG. 6 (a-1), the columnar microdomains 203 are regularly arranged in a hexagonal manner with a natural period do. A microdomain 203 is formed on the chemical mark 205 surrounded by a solid circle. In addition, the portion of the chemical mark 205 where the defect exists (the portion not surrounded by the solid circle in FIG. 6A-1) is the same as the polymer block of the defective portion where the microdomain 203 of the columnar body around the defect is present. Restrains the microphase separation structure of the polymer composition. As a result, as shown in FIG. 6A-2, since the columnar microdomains 203 are oriented perpendicularly to the substrate 201, the defective portion is interpolated.

  On the other hand, for example, in the case where the polymer block copolymer B is not included but only the polymer block copolymer A is present, as shown in FIG. As shown in FIG. 6B-2, microphase separation is performed so that the microdomain 203 is parallel to the substrate 201 at the defect portion. The reason is considered to be that when there are many defect parts, the microdomains 203 of the columnar bodies gather on the surface and a portion parallel to the substrate 201 is generated.

In this embodiment, the chemical mark 205 is interpolated by using a polymer block copolymer composition containing at least the polymer block copolymer A and the polymer block copolymer B. As will be described later, the microdomain 203 is preferably made perpendicular to the substrate 201 by controlling the film thickness of the polymer block copolymer composition formed on the substrate 201 in the first step. It is surely oriented. As a result, the polymer thin film having a fine structure in this embodiment can improve the long-range order of the microphase separation structure and reduce defects.
And by using the polymer block copolymer composition in the present embodiment, the interpolation rate of the defect portion is improved, and the pattern member represented by the density of the microdomain 203 and the density of the chemical mark 205 is improved. When the ratio to the density is defined as n: 1, n can be a number exceeding 1, and n can be 4 or more. Further, by setting n to 16 or less, it is possible to more reliably achieve the interpolation of the defective portion.
If the pattern members on the surface of the substrate 201 are arranged with an average period ds, this average period ds is a natural number times the natural period do of the microdomain 203 (the natural period do of the polymer block copolymer). It is desirable that

  A typical example of a pattern in which the chemical mark 205 can be interpolated by applying the chemical registration method in the present embodiment is shown below. In FIG. 7A referred to here, the chemical marks are arranged over the entire surface of the substrate so as to have the natural period do (hexagonal period) of the polymer block copolymer composition in the present embodiment. FIG. 7B is a conceptual diagram showing a state when the polymer block copolymer composition is microphase-separated, and the polymer block is arranged so that the defect rate of the chemical mark is 25%. FIG. 7 (c) is a conceptual diagram showing a state when the copolymer composition is microphase-separated, and the polymer block copolymer composition is arranged so that the defect rate of chemical marks is 50%. FIG. 7 (d) is a conceptual diagram showing the state of the microphase separation of the polymer block, and the polymer block copolymer composition is microphase-separated by arranging so that the defect rate of the chemical mark is 75%. It is a conceptual diagram which shows the mode at the time of hitting.

  As shown in FIG. 7A, when a substrate 201 in which chemical marks 205 are arranged in hexagonal (chemical mark defect rate 0%) is used, the polymer block copolymer composition in the present embodiment is The microdomain 203 is made to stand upright at a position (hexagonal natural period do) corresponding to the chemical mark 205 by microphase separation.

  As shown in FIG. 7B, when the substrate 201 arranged so that the defect rate of the chemical mark 205 is 25% is used, the polymer block copolymer composition in the present embodiment is Restrained by the upright microdomain 203 around the defect portion of the target mark 205, the microdomain 203 is set upright at a position corresponding to the defect portion of the chemical mark 205. That is, the defective part of the chemical mark 205 is interpolated by using the polymer block copolymer composition in the present embodiment, and chemical registration is realized with high accuracy.

  Further, as shown in FIG. 7C, the substrates 201 arranged so that the defect rate of the chemical marks 205 is 50% (pattern density 1/2), more specifically, the chemical marks 205 are arranged every other row. When the arranged substrate 201 is used, the polymer block copolymer composition in the present embodiment is constrained by the upright microdomains 203 around the defect site of the chemical mark 205, and the defect site of the chemical mark 205. The microdomain 203 is erected at a position corresponding to. That is, the defective part of the chemical mark 205 is interpolated by using the polymer block copolymer composition in the present embodiment, and chemical registration is realized with high accuracy.

  Further, as shown in FIG. 7D, the substrates 201 arranged so that the defect rate of the chemical marks 205 is 75% (pattern density ¼), more specifically, the chemical marks arranged in every other row. When the substrate 201 in which every other 205 is arranged is used, the polymer block copolymer composition in this embodiment has a weak binding force of the microdomain 203 upright around the defect portion of the chemical mark 205. However, the microdomain 203 is erected at a position corresponding to the defect site of the chemical mark 205. That is, the defective part of the chemical mark 205 is interpolated by using the polymer block copolymer composition in the present embodiment, and chemical registration is realized with high accuracy.

(Film formation and microphase separation of polymer block copolymer composition)
A method for forming a microphase separation by forming a polymer block copolymer composition on a chemically patterned substrate 201 will be described below.

  First, the polymer block copolymer composition is dissolved in a solvent to obtain a dilute polymer block copolymer composition solution. Next, a polymer block copolymer composition solution is applied to the surface of the chemically patterned substrate 201 as shown in FIG. The coating method is not particularly limited, and a method such as a spin coating method or a dip coating method may be used. In the case of using the spin coating method, for example, if the concentration of the solution is about several mass% and the rotation speed is 1000 to 5000 rotations per minute, this coating film is dried to have a polymer block having a film thickness of several tens of nm. A thin film of the copolymer composition can be obtained stably.

The film thickness t (dry film thickness) of the polymer block copolymer composition is expressed by the following relational expression (2):
(M + 0.3) × do <t <(m + 0.7) × do (2)
(In the relational expression (2), m represents an integer of 0 or more)
It is desirable to set so as to satisfy.

Thus, by setting the film thickness t of the polymer block copolymer composition, the chemical registration method can be carried out with higher accuracy.
Here, m in the relational expression (2) does not particularly limit the upper limit, but in order to maximize the effect of the chemical registration method, the natural period do of the polymer block copolymer composition is used. Is preferably about 5 times or less, that is, 0 or more and 5 or less.

  The structure of the polymer block copolymer composition formed on the surface of the chemically patterned substrate 201 is generally not an equilibrium structure, although it depends on the film forming method. That is, with the rapid vaporization of the solvent during film formation, the microphase separation of the polymer block copolymer composition did not proceed sufficiently, and the structure was frozen in a non-equilibrium state or in a completely disordered state. It is often a state. Therefore, the substrate 201 is annealed in order to sufficiently advance the microphase separation process of the polymer block copolymer composition and obtain an equilibrium structure. As the annealing, for example, thermal annealing that is left in a state of being heated to a temperature higher than the glass transition temperature of the polymer block copolymer composition, or a solvent that is left in a state of being exposed to the good solvent vapor of the polymer block copolymer composition. Annealing etc. are mentioned. In the case of a polymer block copolymer composition comprising PS-b-PMMA as a main component, thermal annealing is simple, and thermal annealing is performed by heating at a temperature of 170 to 200 ° C. for several hours to several days in a vacuum atmosphere. Is completed.

(Pattern medium)
Next, a patterned medium obtained using the polymer thin film M will be described. FIGS. 8A to 8F referred to here are process diagrams for explaining a method of manufacturing a patterned medium using a polymer thin film having a microstructure in the present embodiment. In FIGS. 8 (a) to 8 (f), surfaces having chemically different properties existing in a patterned state are omitted. In the following description, the pattern medium refers to a medium on which a concavo-convex surface corresponding to a regularly arranged pattern of a microphase separation structure is formed.

In this manufacturing method, as shown in FIG. 8A, a polymer thin film M having a microphase separation structure composed of a continuous phase 204 and columnar microdomains 203 is prepared. Reference numeral 201 denotes a substrate.
Next, in this manufacturing method, as shown in FIG. 8 (b), the micro domain 203 (see FIG. 8 (a)) is removed, so that a porous thin film in which a plurality of micropores H are regularly arranged. The pattern medium 21 is obtained as D.
Note that here, it is only necessary to remove either the continuous phase 204 or the microdomain 203. Although not shown, the patterned medium has a plurality of columnar bodies formed by removing the continuous phase 204 of the microphase separation structure. It may be regularly arranged.

  As a method for removing either the continuous phase 204 of the polymer thin film M or the microdomain 203 of the columnar body, an etching rate between the continuous phase 204 and the microdomain 203 by reactive ion etching (RIE) or other etching methods is used. A method using the difference between the two is mentioned.

  Thus, as the polymer block copolymer capable of forming a polymer thin film capable of selectively removing only one of the polymer phases, in addition to the polymer block copolymer A described above, for example, a polybutadiene block -Polydimethylsiloxane, polybutadiene-block-poly-4-vinylpyridine, polybutadiene-block-polymethyl methacrylate, polybutadiene-block-poly-t-butyl methacrylate, polybutadiene-block-poly-t-butyl acrylate, poly-t-butyl methacrylate -Block-poly 4 vinyl pyridine, polyethylene-block-polymethyl methacrylate, poly-t-butyl methacrylate-block-poly 2 vinyl pyridine, polyethylene-block-poly 2 vinyl pyridine, polyethylene-block -Poly-4-vinylpyridine, polyisoprene-block-poly-2-vinylpyridine, poly-t-butylmethacrylate-block-polystyrene, polymethylacrylate-block-polystyrene, polybutadiene-block-polystyrene, polyisoprene-block-polystyrene, polystyrene poly- Block-poly-2-vinylpyridine, polystyrene-block-poly-4-vinylpyridine, polystyrene-block-polydimethylsiloxane, polystyrene-block-poly-N, N-dimethylacrylamide, polybutadiene-block-sodium polyacrylate, polybutadiene-block- Polyethylene oxide, poly-t-butyl methacrylate-block-polyethylene oxide, polystyrene-block-polyacrylic acid, etc. And the like.

  It is also possible to improve the etching selectivity by doping a metal atom or the like into one of the polymer phases of the continuous phase 204 and the microdomain 203. In the case of a polymer block copolymer such as polystyrene-block-polybutadiene, the polymer phase made of polybutadiene is more easily doped with osmium than the polymer phase made of polystyrene. Using this effect, it is possible to improve the etching resistance of the domain made of polybutadiene.

  The patterned medium 21 is obtained by removing the one of the continuous phase 204 and the microdomain 203 and then etching the substrate 201 using either the remaining continuous phase 204 or the microdomain 203 as a mask. It may be what was made.

  That is, the substrate 201 is etched by RIE or plasma etching using the remaining polymer phase (porous thin film D) as in the continuous phase 204 shown in FIG. 8B as a mask. As a result, as shown in FIG. 8C, the surface portion of the substrate 201 corresponding to the portion of the polymer phase removed through the fine holes H is processed, and the pattern of the micro separation structure is formed on the surface of the substrate 201. It will be transcribed. Then, when the porous thin film D remaining on the surface of the pattern medium 21 is removed by RIE or a solvent, as shown in FIG. 8D, the micropores H having a pattern corresponding to the microdomain 203 of the columnar body are formed on the surface. Thus, the patterned medium 21a formed in the above is obtained.

Further, the pattern medium 21 may be copied by transferring the pattern arrangement using the pattern medium 21 as an original plate.
That is, the other polymer phase (porous thin film D) remaining like the continuous phase 204 shown in FIG. 8B is brought into close contact with the transfer target 30 as shown in FIG. The structure pattern is transferred to the surface of the transfer target. Thereafter, as shown in FIG. 8 (f), the pattern of the porous thin film D (see FIG. 8 (e)) is transferred by peeling the transfer target 30 from the pattern medium 21 (see FIG. 8 (e)). A replica (pattern medium 21b) can be obtained.

  Here, the material of the transfer target 30 may be selected according to the use, such as nickel, platinum, gold or the like if it is a metal, or glass or titania if it is an inorganic material. When the transfer object 30 is made of metal, the transfer object 30 can be brought into close contact with the uneven surface of the pattern substrate by sputtering, vapor deposition, plating, or a combination thereof.

  In addition, when the transfer target 30 is an inorganic substance, it can be adhered by using, for example, a sol-gel method in addition to sputtering or a CVD method. Here, the plating method and the sol-gel method are preferable methods because they can accurately transfer a regular array pattern of several tens of nanometers in a microphase-separated structure, and the cost can be reduced by a non-vacuum process. is there.

  The patterned media 21, 21 a, 21 b obtained by the above-described manufacturing method are applied to various uses because the uneven surface of the pattern formed on the surface is fine and the aspect ratio is large.

  For example, replicas of the patterned media 21, 21a, and 21b having the same regular arrangement pattern on the surface are obtained by repeatedly bringing the surface of the manufactured patterned media 21, 21a, and 21b into close contact with the transfer target by nanoimprinting or the like. Can be used for applications such as manufacturing a large amount.

Hereinafter, a method for transferring a fine pattern on the concave and convex surfaces of the pattern media 21, 21a, and 21b to the transfer target 30 by the nanoimprint method will be described.
The first method is a method of imprinting the produced pattern media 21, 21a, 21b directly onto the transfer target 30 to transfer a regular array pattern (this method is called a thermal imprint method). This method is suitable when the transfer target 30 is made of a material that can be directly imprinted. For example, when a thermoplastic resin typified by polystyrene is used as the transfer target 30, the pattern medium 21, 21a, 21b is pressed against the transfer target 30 after the thermoplastic resin is heated to a glass transition temperature or higher. Then, after cooling to the glass transition temperature or lower and releasing the pattern media 21, 21a, 21b from the surface of the transfer target 30, a replica can be obtained.

  As a second method, when the pattern media 21, 21a, 21b are made of a light-transmitting material such as glass, a photo-curing resin is applied as a transfer target (not shown) (this method, Called the optical imprint method). When light is applied after the photo-curable resin is brought into close contact with the pattern media 21, 21a, 21b, the photo-curable resin is cured. Therefore, the pattern media 21, 21a, 21b are released, and the light after curing is cured. A curable resin (transfer object) can be used as a replica.

  Further, in such a photoimprint method, when a substrate such as glass is used as a transfer target (not shown), a photo-curable resin is brought into close contact with a gap between the pattern substrate and the transfer target substrate. Irradiate light. Then, after curing the photocurable resin, the pattern substrate is released, and the cured photocurable resin having irregularities on the surface is used as a mask, and etching is performed with plasma, ion beam, or the like. There is also a method of transferring a regular arrangement pattern on the top.

(Pattern medium for magnetic recording)
Next, reference will be made to a magnetic recording medium as an example of a device realized by the present invention. Magnetic recording media are always required to improve data recording density. For this reason, the dots on the magnetic recording medium, which is a basic unit for engraving data, are also miniaturized and the interval between adjacent dots is narrowed to increase the density.
Incidentally, in order to construct a recording medium having a recording density of 1 terabit / square inch, it is said that the period of the dot arrangement pattern needs to be about 25 nm. Thus, as the density of dots increases, there is a concern that the magnetism applied to turn on / off one dot affects adjacent dots.
Therefore, in order to eliminate the influence of magnetism leaking from adjacent dots, a pattern medium (not shown) in which the dot area on the magnetic recording medium is physically divided has been studied.

  The pattern media 21, 21a, and 21b described above can be used as such a pattern medium or a master for manufacturing the pattern medium. In particular, the patterned medium for magnetic recording needs to arrange minute irregularities on the entire surface of the disk without defects and regularly. The present invention is effective for improving the throughput when a chemical pattern is drawn on the entire surface of the disk.

Next, the present invention will be described more specifically with reference to examples.
Here, a polymer block copolymer composition composed of two types of PS-b-PMMA having different molecular weights was applied onto a substrate.

<Patterning of substrate>
A Si wafer having a natural oxide film was used as the substrate. After polystyrene was grafted on the entire surface of the substrate, the polystyrene graft layer formed on the surface of the substrate was patterned by electron beam (EB) lithography. The substrate was patterned to have a surface with different wettability for polystyrene and polymethylmethacrylate.

The procedure will be described in more detail below.
A substrate grafted with polystyrene was prepared by the following method. First, a Si wafer (4 inches (102 mm)) having a natural oxide film was cleaned with a piranha solution. Since the piranha treatment has an oxidizing action, organic substances on the surface of the substrate are removed, and the hydroxyl group density on the surface is increased by oxidizing the surface of the Si wafer. Next, a toluene solution (concentration: 1.0% by mass) of polystyrene (PS-OH) having a hydroxyl group at the molecular chain terminal is applied to the surface of the Si wafer using a spin coater (Mikasa Co., Ltd., 1H-360S). did. The rotation speed of the spin coater was 3000 rpm. The molecular weight of PS-OH used was 3700. The film thickness (dry film thickness) of PS-OH obtained on the substrate was about 50 nm.

  Next, the substrate coated with PS-OH was heated in a vacuum oven at 140 ° C. for 48 hours. By this heat treatment, the terminal hydroxyl group of PS-OH was chemically bonded to the hydroxyl group on the surface of the substrate by a dehydration reaction. Finally, unreacted PS-OH was removed from the substrate. The removal of PS-OH was performed by immersing the substrate in toluene and performing ultrasonic treatment.

  In order to evaluate the surface state of the substrate grafted with polystyrene, the thickness of the polystyrene graft layer, the amount of carbon on the surface of the substrate, and the contact angle of polystyrene with respect to the surface of the substrate were measured. Spectroscopic ellipsometry was used to measure the thickness of the polystyrene graft layer. X-ray photoelectron spectroscopy (XPS method) was used for quantification of the amount of carbon. The thickness of the polystyrene graft layer was 5.1 nm. The amount of carbon on the surface of the substrate before and after the grafting of polystyrene was 4500 cps and 27000 cps as the integrated intensity of the peak derived from the C1S.

The contact angle of polystyrene was measured using the following method.
First, a homopolystyrene (hPS) thin film having a molecular weight of 4000 was applied to the surface of the substrate by spin coating so as to have a thickness of about 80 nm.

  Next, the substrate on which the hPS film was formed was annealed at a temperature of 170 ° C. for 24 hours in a vacuum atmosphere. By this annealing, the hPS thin film was dewetting on the surface of the substrate to form minute hPS droplets. After this annealing by heating, the shape of the hPS droplet was frozen by immersing the substrate in liquid nitrogen and quenching the droplet from the heating temperature. Then, the cross-sectional shape of the droplet was observed with an atomic force microscope, and the contact angle of hPS with respect to the substrate at the heating temperature during annealing was determined by measuring the angle of the interface between the substrate and the droplet. At this time, the angle was measured for 6 points, and the average value was taken as the contact angle.

The contact angle of hPS was 9 degrees. That is, the contact angle with respect to the Si wafer before grafting was smaller than 35 degrees. From this, it was confirmed that a polystyrene graft layer could be formed on the surface of the Si wafer.
Next, the polystyrene graft layer of the substrate was patterned by EB lithography. FIG. 9A referred to here is a plan view showing a partially enlarged polystyrene graft layer, and FIG. 9B is a plan view schematically showing the arrangement of regions having different lattice spacings d. It is.

  As shown in FIG. 9A, the surface of the patterned polystyrene graft layer 207 is exposed in a circular shape with a radius r, which will be described later, of the underlying Si wafer 209, and the lattice spacing which will be described later. The polystyrene graft layer 207 is partially removed so as to be arranged hexagonally at d.

  In the patterning described above, as shown in FIG. 9B, the lattice spacing d is 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, and 58 nm for each region that divides the surface of the polystyrene graft layer 207 by 100 μm square. Thus, the above-described circular exposed portion was formed. In addition, the radius r of the circular shape of the partitioned area was set to be approximately 25% to 30% of each lattice interval d.

Next, the patterning method of the substrate 201 having a polystyrene graft layer will be described more specifically with reference to FIGS. 4B to 4G as appropriate.
Here, the substrate 201 shown in FIG. 4B is a Si wafer and the chemically modified layer 401 is a polystyrene graft layer, which is diced into a size of 2 cm square and used.

  Then, as shown in FIG. 4C, a resist film 402 made of polymethyl methacrylate was formed on the surface of the polystyrene graft layer (chemically modified layer 401) by spin coating so as to have a thickness of 85 nm.

  Next, as shown in FIG. 4D, the resist film 402 was exposed to correspond to the above-described pattern at an acceleration voltage of 100 kV using an EB lithography apparatus. Here, the radius r of the pattern (circular shape) was adjusted by the exposure amount of EB at each lattice point. Then, as shown in FIG. 4E, the resist film 402 was developed.

Next, as shown in FIG. 4F, using the patterned resist film 402 as a mask, the polystyrene graft layer (chemically modified layer 401) was etched by reactive dry etching (RIE) using oxygen gas. The RIE was performed using an ICP dry etching apparatus. At this time, the output of the apparatus was set to 40 W, the oxygen gas pressure was set to 4 Pa, the oxygen gas flow rate was set to 30 cm ³ / min, and the etching time was set to 5 to 10 seconds.
Then, as shown in FIG. 4G, by removing the resist film 402 remaining on the surface of the substrate 201 with toluene, the substrate 201 having a polystyrene graft layer (chemically modified layer 401) patterned on the surface is obtained. Obtained.

(Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2)
Here, two types of PS-b-PMMA shown in Table 1 were selected from four types of PS-b-PMMA to prepare a polymer block copolymer composition.

First, the four types of PS-b-PMMA used will be described.
The polymer block copolymer A contained as a main component in the polymer block copolymer composition has a number average molecular weight Mn (A2) of polystyrene chain as the polymer block chain A2 of 35500, and the polymer block chain A1. The number average molecular weight Mn (A1) of the polymethylmethacrylate chain was 12200. The molecular weight distribution Mw / Mn as a whole of PS-b-PMMA was 1.04. In Table 1, this main component is described as PS (36k) -b-PMMA (12k).

  This polymer block copolymer A is made of polymethyl methacrylate because the number average molecular weight Mn (A2) of the polystyrene chain is 35500 and the number average molecular weight Mn (A1) of the polymethyl methacrylate chain A1 is 12200. The micro domains of the columnar body form a micro phase separation structure arranged in a continuous phase composed of polystyrene.

For this polymer block copolymer A, as shown in Table 1, in Examples 1 and 2 and Comparative Example 2, the polymer block copolymer was used with the following three types of PS-b-PMMA as subcomponents: It is included in the combined composition.
In Comparative Example 1, only the above-described polymer block copolymer A is used.

PS-b-PMMA (corresponding to the above-described polymer block copolymer B) used as an accessory component in Example 1 has a number average molecular weight Mn (B2) of polystyrene chain as the polymer block chain B2 of 46100. The number average molecular weight Mn (B1) of the polymethyl methacrylate chain as the polymer block chain B1 was 21,000. The molecular weight distribution Mw / Mn as a whole of PS-b-PMMA was 1.09. In Table 1, this subcomponent is described as PS (46k) -b-PMMA (21k).
Therefore, the polymer block copolymer composition in Example 1 satisfies the above-described relational expression (1).

PS-b-PMMA (corresponding to the above-described polymer block copolymer B) used as an auxiliary component in Example 2 has a number average molecular weight Mn (B2) of polystyrene chain as the polymer block chain B2 of 52,000. The number average molecular weight Mn (B1) of the polymethyl methacrylate chain as the polymer block chain B1 was 52,000. The overall molecular weight distribution Mw / Mn of PS-b-PMMA was 1.10. In Table 1, this subcomponent is described as PS (52k) -b-PMMA (52k).
Therefore, the polymer block copolymer composition in Example 2 satisfies the above-described relational expression (1).

PS-b-PMMA used as an accessory component in Comparative Example 2 has a polystyrene chain number average molecular weight Mn of 12800 corresponding to the polymer block chain B2, and a polymethyl methacrylate chain corresponding to the polymer block chain B1. The number average molecular weight Mn was 12900. The molecular weight distribution Mw / Mn as a whole of PS-b-PMMA was 1.05. In Table 1, this subcomponent is described as PS (13k) -b-PMMA (13k).
The polymer block copolymer composition in Comparative Example 2 does not satisfy the above-described relational expression (1).

<Measurement of natural period do of polymer block copolymer composition>
The natural period do of each polymer block copolymer composition (PS-b-PMMA composition) shown in Table 1 was determined by the following method. First, a PS-b-PMMA composition sample shown in Table 1 was dissolved in semiconductor grade toluene to obtain a 1.0 mass% toluene solution of the PS-b-PMMA composition.

  Next, this solution was applied to the surface of a substrate made of silicon by a spin coater method to form a thin film having a dry film thickness of 45 nm. Then, the substrate was annealed at 170 ° C. for 24 hours using a vacuum oven, so that the PS-b-PMMA composition on the substrate developed a self-organized structure in an equilibrium state by microphase separation. The micro phase separation structure of the self-organized PS-b-PMMA composition was observed using a scanning electron microscope (SEM).

SEM observation was carried out under the condition of an acceleration voltage of 0.7 kV using S4800 manufactured by Hitachi, Ltd. A sample for SEM observation was prepared by the following method.
First, columnar microdomains present in the thin film of the PS-b-PMMA composition were decomposed and removed by an oxygen RIE method. As a result, a polymer thin film having a nanoscale uneven shape derived from a microphase separation structure was obtained. RIE-10NP manufactured by Samco Corporation was used for RIE. At this time, the oxygen gas pressure was set to 1.0 Pa, the oxygen gas flow rate was set to 10 cm ³ / min, the apparatus output was set to 20 W, and the etching time was set to 30 seconds.
In order to accurately measure the fine structure, the necessary contrast was obtained by adjusting the acceleration voltage without performing deposition of Pt or the like on the surface of the sample, which is usually performed for the prevention of charging in SEM observation.

FIG. 10A is an SEM photograph of the microphase separation structure in Example 1, and FIG. 10B is a photograph of a two-dimensional Fourier transform image of the microdomains of the columnar bodies arranged in Example 1.
As shown in FIG. 10A, the PS-b-PMMA composition used in Example 1 has hexagonal arrangement of columnar microdomains upright with respect to the substrate.
The natural period do of the PS-b-PMMA composition was determined based on such an SEM observation image.

  The natural period do was determined by two-dimensional Fourier transform of the SEM observation image using general-purpose image processing software. As shown in FIG. 10B, since the two-dimensional Fourier transform image of the microdomains of the columnar bodies arranged on the substrate gave a halo pattern in which a large number of spots were gathered, the natural period do from the first halo radius. Was decided. The natural period do determined for each PS-b-PMMA composition is shown in Table 1.

<Chemical registration method>
Using a method similar to the determination of the natural period do of the polymer block copolymer composition described above, a self-assembled thin film of the PS-b-PMMA composition is formed on the surface of the chemically patterned substrate, The pattern shape in the thin film of the obtained PS-b-PMMA composition was observed with a scanning electron microscope.

  A representative result is shown in FIG. First, on the substrate chemically patterned with a lattice spacing d = 48 nm in FIG. 11A, PS (36k) -b-PMMA (12k) is self-organized to form a column between chemical patterns. The SEM observation result when the structure can be interpolated is shown. The position of the micro domain of the columnar body made of polymethyl methacrylate formed by PS-b-PMMA is constrained by selectively getting wet to the exposed portion of the Si wafer on the surface of the chemically patterned substrate. The continuous phase made of polystyrene formed by PS-b-PMMA selectively wets the polystyrene graft layer on the surface of the patterned substrate. Further, between the patterns, the PS-b-PMMA is controlled to have a film thickness, so that the columnar bodies are oriented perpendicular to the substrate, so that the arrangement of the columnar bodies between the patterns is exposed to the surrounding Si wafer. It can be seen that it is constrained by the columnar bodies regularly arranged in the part and periodically arranged over a long distance.

  In contrast, FIG. 11B shows a typical pattern in the case where the pattern interpolation by the chemical registration method is incomplete. The SEM image shown in FIG. 11B is a structure that is often observed when the film thickness of the polymer thin film is close to the natural period do of the polymer, and a part of the pattern interpolation is the same as in FIG. However, in the portion where the Si wafer is not exposed, that is, between the patterns, a large number of regions where the columnar body is not vertically aligned with respect to the substrate were observed.

FIG. 11 (c) shows an example in which pattern interpolation is hardly recognized in the self-organization of PS (36k) -b-PMMA (12k).
Next, PS-b-PMMA composition for quadruple density by interpolating between lattice points using a chemically patterned substrate with double lattice spacing d using FIG. And the representative result which examined the influence of film thickness is shown.

  12 (a-1) and 12 (a-2) are SEM images of a polymer thin film obtained using a single PS (36k) -b-PMMA (12k) system. The natural period do of this system is 24 nm, FIG. 12A-1 has a film thickness of 25 nm, and FIG. 12A-2 has a film thickness of 38 nm. Since the natural period do of the single system PS (36k) -b-PMMA (12k) is 24 nm, the film thickness is approximately 1.0 period in FIG. 12 (a-1) and 1 in FIG. 12 (a-2). Corresponds to 5 cycles. First, in FIG. 12 (a-2), pattern interpolation by the almost complete chemical registration method was observed. On the other hand, in FIG. 12 (a-1), the portion where the Si wafer is not exposed, that is, between the patterns, the columnar body is almost not vertically aligned with respect to the substrate. The pattern interpolation by the modulation method was not realized.

  Next, in FIGS. 12B-1 and 12B-2, PS (36k) -b-PMMA (12k) is the main component and PS (46k) -b-PMMA (21k) is the subcomponent. Is a SEM image of a polymer thin film obtained using a system blended at a weight ratio of 80:20. The natural period do of this system is 26 nm, FIG. 12B-1 shows a film thickness of 26 nm, and FIG. 12B-2 shows a film thickness of 40 nm. Since the natural period of PS (36k) -b-PMMA (12k) single system is 24 nm, FIG. 12 (b-1) shows a film thickness of approximately 1.0 period, and FIG. This corresponds to 5 cycles. First, in FIG. 12 (b-2), pattern interpolation by an almost complete chemical registration method was observed as in FIG. 12 (a-1). On the other hand, in FIG. 12 (b-1), the portion where the Si wafer is not exposed, that is, between the patterns, the state where the cylinder is not vertically aligned with respect to the substrate and the chemical registration method are realized. The result is a mixture of different areas.

Next, the status of the chemical registration method was evaluated based on the SEM image using the following indices. First, the interpolation rate by the chemical registration method was defined as follows and determined from the SEM image.
Interpolation rate (%) = number of interpolated grid points / number of chemical pattern drawing defects on substrate

  In the case where the interpolation rate was close to 100%, the accuracy of the pattern obtained by the chemical registration method was obtained by the method shown in FIG. First, the position of the barycenter of the lattice was determined from the SEM image shown in FIG. 13A by image processing, and an image showing the distribution was determined. Then, the image was two-dimensional Fourier transformed. Next, each pixel of the obtained two-dimensional Fourier transform image is squared and the inverse Fourier transform is performed to obtain a two-dimensional autocorrelation function image of the barycentric distribution image of the lattice shown in FIG. It was. Further, the two-dimensional autocorrelation function image shown in FIG. 13C was subjected to an annular average process centered on the image center to determine the radial distribution function of the center of gravity shown in FIG. By fitting the primary peak of this radial distribution function with a Gaussian function, the standard deviation of the primary peak, that is, the standard deviation of the distance between the closest lattices, was obtained and used as the pattern accuracy. Then, the interpolation rate and pattern accuracy for the examples and comparative examples shown in Table 1 are obtained, and the results are shown in Table 1.

  First, when the film thickness t of the polymer block copolymer composition is about 1.5 times the natural period do, an interpolation rate of almost 100% can be achieved, and good pattern interpolation can be achieved. found.

  In terms of pattern accuracy, in the system in which PS (46k) -b-PMMA (21k) is mixed by 10% by weight or 20% by weight as a subcomponent, compared to the PS (36k) -b-PMMA (12k) single system It has been found that a smaller value, i.e. a more accurate pattern, can be obtained.

  When the film thickness t of the polymer block copolymer composition is about 1.0 times the natural period do, PS (36k) -b-PMMA (12k) single system and PS (36k)- In a system in which 10% by weight of PS (13k) -b-PMMA (13k) as a sub-component was mixed with b-PMMA (12k), the interpolation rate was about 5%, and it was found that pattern interpolation could hardly be realized.

In contrast, a system in which PS (36k) -b-PMMA (12k) is the main component and PS (46k) -b-PMMA (21k) is mixed as a minor component at 10 wt% or 20 wt%, or PS In a system in which (36k) -b-PMMA (12k) is the main component and PS (52k) -b-PMMA (52k) is mixed at 10% by weight as a subcomponent, the interpolation rate is 60 to 75%, which is a significant improvement. Admitted.
Even in a system in which PS (36k) -b-PMMA (12k) is a main component and PS (46k) -b-PMMA (21k) is mixed as a subcomponent, the weight fraction of the subcomponent is 30%. The pattern interpolation rate was not improved.

  From the above results, when the polymer block copolymer composition satisfies the relational expression (1), and desirably the mass fraction of the secondary component is in the range of 5% to 25%, the chemical registration method It has been found that the pattern interpolation rate by is improved.

  Further, generally good pattern interpolation is performed when the film thickness t of the polymer block copolymer composition layer and the natural period do of the polymer block copolymer composition satisfy the relational expression (2). Was found to be feasible.

  Even in this case, when the polymer block copolymer composition satisfies the relational expression (1), and the weight fraction of the subcomponent is preferably in the range of 5% to 25%, the pattern accuracy is further improved. It was found that a high pattern can be formed.

(Example 3)
In the above examples and comparative examples, the lattice interval d of the substrate of the chemical pattern is set to twice the natural period do of PS-b-PMMA. Next, the lattice interval d of the substrate is changed to that of PS-b-PMMA. Example 3 was examined as a case where the natural period was 3 times the natural period do. The experiment was carried out by using the same polymer block copolymer composition as in Example 1 except that a substrate having a chemical pattern having a period d three times the natural period do was used. That is, since the natural period do of the polymer block copolymer composition was 26 nm, the substrate was prepared so that the period d of the chemical pattern of the substrate was 78 nm. The film thickness was 40 nm corresponding to about 1.5 times the natural period do. The obtained results are shown in Table 1. In this study, the defect rate of the chemical mark was a very large value of 89%, but the obtained interpolation rate was 100%. This result shows that the density of the pattern can be increased by 9 times by applying the present invention.
As described above, by using the PS-b-PMMA composition having the molecular weight and the mixing ratio defined in the present invention and defining the film thickness, the columnar cylinders are regulated by self-organization during the lattice spacing d. It was shown that it was possible to arrange them automatically. As a result, not only can the throughput of direct writing of chemical patterns be improved, but also the density of the pattern can be increased by self-organization, thus breaking the limits of the current top-down lithography technology, This result suggests that there is a possibility that a finer pattern can be formed uniformly.

Example 4
Next, the Example which manufactured the pattern board | substrate is shown. First, an example in which the microdomain of the columnar body in the polymer thin film M is decomposed and removed to form a porous thin film on the surface of the substrate according to the steps shown in FIGS.

  In accordance with the procedure of Example 1 in which the mass fraction of the subcomponent is 20%, a polymer thin film M in which the microdomains of the columnar body made of polymethyl methacrylate are upright (oriented in the film thickness direction) with respect to the film surface is formed on the substrate. Produced. Here, the pattern is arranged as shown in FIG.

  The polymer block copolymer composition is applied to a chemically patterned substrate with a lattice spacing d twice as large as the natural period do of the polymer block copolymer composition so that the film thickness is 38 nm. By applying, microphase separation was expressed. As a result, a structure was obtained in which the columnar microdomains 203 made of polymethylmethacrylate were regularly arranged in the continuous phase 204 made of polystyrene (see FIG. 8A).

  Next, an operation of removing the microdomains 203 by RIE was performed to obtain a porous thin film D (pattern medium) (see FIG. 8B). Here, the oxygen gas pressure was set to 1 Pa, the output was set to 20 W, and the etching time was set to 90 seconds.

  The surface shape of the produced porous thin film D was observed with a scanning electron microscope. As a result, it was confirmed that columnar fine holes H were formed in the porous thin film D over the entire surface and oriented in the thickness direction of the film. Here, the diameter of the micropore H was about 15 nm. Furthermore, as a result of detailed analysis of the arrangement state of the micropores H in the obtained porous thin film D, the micropores H are free from defects in a region where the surface is chemically patterned with a period d = 24 nm, and are unidirectional. It can be seen that they are arranged in hexagonal in an oriented state.

  On the other hand, in the region that is not chemically patterned, the micropores H are microscopically arranged in a hexagonal manner, but macroscopically, the region that is arranged in a hexagonal manner forms grains. In particular, it has been found that many lattice defects exist in the grain interface region.

  Then, a part of the porous thin film D was peeled off and removed from the surface of the substrate 20 with a sharp blade, and when the step between the surface of the substrate 201 and the surface of the porous thin film D was measured by AFM observation, the value was about 30 nm. there were.

  The aspect ratio of the obtained micropore H was 2.0, and it was confirmed that a large value that cannot be obtained in the spherical microdomain was realized. The thickness of the polymer thin film M, which was 36 nm before the RIE, was reduced to 30 nm because of the continuous domain made of polystyrene together with the columnar microdomains 203 made of polymethylmethacrylate by the RIE. This is probably because phase 204 was also slightly etched.

Next, according to the steps shown in FIGS. 8C and 8D, the pattern was transferred to the substrate 201 using the porous thin film D (pattern medium). That is, the pattern of the porous thin film D was transferred to the substrate 201 by etching the substrate 201 using the porous thin film D as a mask. Here, the etching was performed by dry etching with CF ₄ gas. As a result, the shape and arrangement of the micropores H in the porous thin film D could be transferred to the substrate 201.

(A) to (d) are process explanatory views of a method for producing a polymer thin film having a microstructure according to an embodiment of the present invention. It is a conceptual diagram which shows the mode of the polymer block chain in a polymer block copolymer composition. (A) is a perspective view schematically showing a state in which a polymer block copolymer composition forms a columnar pattern structure by microphase separation, and (b) is a polymer block copolymer composition. FIG. 2 is a perspective view schematically showing a state in which a phase structure of a plate-like body is formed by microphase separation. (A) to (g) is a process explanatory view of a method for patterning the surface of a substrate. (A) And (b) is a schematic diagram which shows the other aspect by which a chemical modification layer is arrange | positioned on a board | substrate. (A-1) is a conceptual diagram showing how a defect of a chemical mark is interpolated using the polymer block copolymer composition in the present embodiment, and (a-2) is (a-1) It is XX sectional drawing of). (B-1) is a conceptual diagram showing a state in which a defect of a chemical mark is not interpolated using the polymer block copolymer in the comparative example, and (b-2) is a Y- It is Y sectional drawing. In (a), chemical marks are arranged over the entire surface of the substrate so as to be the natural period do (hexagonal period) of the polymer block copolymer composition in this embodiment. The conceptual diagram which shows the mode at the time of carrying out the micro phase separation of the polymer composition, (b) arranges so that the defect rate of a chemical mark may be 25%, and a polymer block copolymer composition is made into a micro phase. The conceptual diagram which shows the mode at the time of making it isolate | separated, (c) arranges so that the defect rate of a chemical mark may be 50%, and shows the mode at the time of carrying out micro phase separation of the polymer block copolymer composition. The conceptual diagram to show, (d) is a conceptual diagram showing a state when the polymer block copolymer composition is microphase-separated by arranging so that the defect rate of the chemical mark is 75%. (A) to (f) are process diagrams for explaining a method for producing a patterned medium using a polymer thin film having a fine structure in the present embodiment. (A) is a top view which expands and shows the patterned polystyrene graft layer partially, (b) is a top view which shows typically arrangement | positioning of the area | region where the lattice spacing d differs. (A) is a SEM photograph of the microphase separation structure in Example 1, and (b) is a photograph of a two-dimensional Fourier transform image of the microdomains of the columnar bodies arranged in Example 1. (A) to (c) are scanning electron micrographs of patterns formed by the polymer block copolymer composition on the surface of a chemically patterned substrate. (A-1), (a-2), (b-1) and (b-2) are scanning patterns formed by the polymer block copolymer composition on the surface of a chemically patterned substrate. It is a type | mold electron micrograph. It is the figure which showed the method of evaluating a pattern precision. It is a conceptual perspective view for demonstrating the conventional method of chemically patterning the surface of a board | substrate.

Explanation of symbols

106 First material 107 Second material 201 Substrate 203 Micro domain 204 Continuous phase 21 Pattern medium 21a Pattern medium 21 Pattern medium 21b Pattern medium 30 Transfer object M Polymer thin film C Polymer block copolymer composition t Film thickness do natural period

Claims (12)

A first step of disposing a polymer layer containing the polymer block copolymer composition on the substrate surface;
A second step of microphase-separating the polymer layer to form regularly arranged microdomains in the continuous phase;
In a method for producing a polymer thin film having a microstructure containing
The polymer block copolymer composition is mainly composed of a polymer block copolymer A composed of at least a polymer block chain A1 and a polymer block chain A2.
A polymer block chain B1 compatible with the polymer phase P1 mainly composed of the polymer block chain A1 and a polymer block chain B2 compatible with the polymer phase P2 mainly composed of the polymer block chain A2. A polymer block copolymer B having
The molecular weight Mn (A1) of the polymer block chain A1, the molecular weight Mn (A2) of the polymer block chain A2, and the molecular weight Mn (B2) of the polymer block chain are expressed by the following relational expression (1) :
Relational expression (1): Mn (A2)> Mn (A1) and Mn (B2)> Mn (A2)
Satisfied,
The substrate surface is formed by discretely arranging pattern members made of the second material on the surface made of the first material,
In the second step, the interfacial tension of the polymer phase P1 with respect to the surface made of the first material is smaller than the interfacial tension with the surface made of the second material, and is high with respect to the surface made of the first material. interfacial tension of molecular phase P2 is much larger than the interfacial tension between the second consists of the material surface,
The dry film thickness t of the coating film of the polymer block copolymer composition on the substrate surface and the natural period do of the microdomain are expressed by the following relational expression (2):
Relational expression (2) (m + 0.3) × do <t <(m + 0.7) × do
(In the relational expression (2), m represents an integer of 3 to 5)
The manufacturing method of the polymer thin film which has the microstructure characterized by satisfying these .   2. The method for producing a polymer thin film having a microstructure according to claim 1, wherein the mass fraction of the polymer block copolymer A in the total composition is 75% or more and 95% or less.   The polymer block chain A1 and the polymer block chain B1 have the same chemical structure, and the polymer block chain A2 and the polymer block chain B2 have the same chemical structure, The manufacturing method of the polymer thin film which has the microstructure of Claim 1 or Claim 2 to do.   The ratio between the density of the microdomains and the density of the pattern member is n: 1 (where n is a number exceeding 1), according to any one of claims 1 to 3. A method for producing a polymer thin film having the microstructure described above.   The method for producing a polymer thin film having a microstructure according to any one of claims 1 to 4, wherein the pattern members are regularly arranged.   The pattern member on the substrate surface is arranged with an average period ds, and the average period ds is a natural number multiple of the natural period do of the microdomain. A method for producing a polymer thin film having the microstructure according to item 1.   The method for producing a polymer thin film having a microstructure according to any one of claims 1 to 6, wherein the microdomain is a columnar body. Either one of the continuous phase and the microdomain of the polymer thin film obtained on the substrate by the method for producing a polymer thin film having a microstructure according to any one of claims 1 to 7 is removed. A pattern medium manufacturing method comprising the step of: The method further includes the step of etching the substrate using either the continuous phase or the microdomain remaining as a mask after removing either the continuous phase or the microdomain. The manufacturing method of the pattern medium of Claim 8 . A microstructure comprising a polymer thin film obtained by the method for producing a polymer thin film having a microstructure according to any one of claims 1 to 7 . A pattern medium obtained by the pattern medium manufacturing method according to claim 8 . A pattern medium, which is reproduced by transferring the pattern arrangement using the pattern medium according to claim 11 as an original plate.